This invention relates to the redistribution of laser beam photons into desired geometric projection patterns, specifically conic and linear laser light projection patterns, for industrial, educational, commercial, and aesthetic applications.
Heretofore, laser light projection patterns have been generated by a method known as laser scanning. Laser scanning involves reflecting an incident laser beam off an electromechanically controlled mirror whose position changes with time. The mirror can be controlled to reflect the beam into a laser light pattern to suit the particular application. Scanning laser beams often work in conjunction with laser photodetectors. The presence or absence of the laser beam at the photodetector may be used to trigger some type of process decision making.
Scanning mirrors are put into motion one of two ways. Mirrors can be rotated, or they can be translated backwards and forwards. There exists a variety of electromechanical means capable of rotating or translating a mirror to give the desired laser pattern. Rotating mirrors are typically connected to an electrical motor. A laser light beam is directed at the rotating mirror. As the mirror's position changes with time, so too does the angle at which the beam strikes the mirror. The laser light projection pattern can be controlled by varying the motor's rotational speed, changing the shape of the mirror, or adding other optical elements.
In engineering practice, electrical motors with attached front surface mirrors are typically employed to create laser scanning projection patterns. These motors can vary in sophistication, depending upon the needs of the laser projection application. Free running AC or DC motors, with passive electrical regulation controls, may be all the hardware required to generate the necessary laser pattern. More sophisticated stepper motors, with precise incremental steps of two degrees or less, may be better suited for more demanding laser projection pattern requirements. Stepper motors with attached mirrors require additional drive electronics support hardware, adding significantly to the costs of generating laser patterns.
A special type of rotary servo motor known as a galvanometer is often employed to create laser projection or scan patterns A galvanometer scanner consists of a limited rotary servo motor that is specifically designed for highly linear torque requirements, along with an attached mirror mounted to the motor. Galvanometer scanners can be designed with moving iron or moving coil elements, to which the front surface mirrors are attached. Certain galvanometer arrangements provide for translational backwards and forwards movement of their front surface mirrors. To obtain more complex laser light patterns, the above described motors can be programmed to generate raster or vector patterns. The desired laser light scanning projection pattern ultimately results from precisely controlling the current flowing through the coil of the chosen electromechanical system at any given moment in time. Laser scanning systems employing motors or galvo's are utilized in industry to resolve a variety of applications. Some of these applications include: bar code identification, vision systems, beam positioning systems, facsimile transmission, optical pointing, alignment and measurement systems, robotic positioning control, security systems, sales promotional, educational, and audio-visual aesthetic effects.
All laser scanning implementation methods for generating laser light projection patterns have common inherent problems. The primary problems with traditional electromechanical laser scanning include the following:
A) Laser scanning involves moving parts. Moving parts pose significant reliability risks. Moving parts are given a MTBF, or mean time between failure rating. As such, the mechanical support for the reflecting mirror is expected to fail over time.
B) Laser scanning systems require the use of precision optics. Front surface mirrors with special protective coatings are required. Special polygon mirrors designs are manufactured to demanding tolerances for implementation in many laser scanning systems. Precision positioning is another requirement for these precision optical subcomponents.
C) Laser scanning systems require large minimum package size. In addition to the laser and the mirror, a variety of support electronics and optics are employed to create the desired laser light projection pattern.
D) Laser scanning systems have undesirable minimum power requirements. The support electronics to position the mirror(s) often requires more power than the scan system's laser beam. Power consumption creates its own heat dissipation problems, resulting in added design time and manufacturing costs.
E) Laser scanning systems create noise while creating the desired laser light pattern. Noise is inherit with the above stated moving parts required to position the scanning mirrors.
F) Laser scanning systems are expensive to design, build, and maintain. A typical electromechanical laser scanning system uses custom parts. These custom parts must be stocked as spare items, adding significant administrative costs to the overall system.